Conventional non-invasive blood pressure (NIBP) monitoring systems generally inflate a pressure cuff above the patient's systolic pressure and measure oscillations in the cuff as the cuff is deflated. The pressure cuff is wrapped around a limb and secured thereto with a fastening mechanism such as, for example, Velcro. After wrapping and securing the pressure cuff to a limb, a cuff bladder is inflated with air in order to apply pressure. The oscillations monitored by the NIBP system are transmitted through the air contained within the cuff bladder during a blood pressure measurement. The volume of air within the bladder can impact the strength of the monitored oscillation signals and correspondingly impact the accuracy of a NIBP measurement.
One problem with conventional NIBP systems is that the process of wrapping the pressure cuff to a limb is operator sensitive. A first operator may take a blood pressure determination by tightly wrapping the pressure cuff around a patient's arm and inflating the cuff bladder with a relatively low air volume, whereas a second operator may take a blood pressure determination by loosely wrapping the pressure cuff around a patient's arm and inflating the cuff bladder with a relatively high air volume. This variation in cuff bladder air volume can impact oscillation signal strength such that a resultant NIBP measurement may become imprecise.
Oscillometric blood pressure monitors used on the upper arm utilize a range of cuff types to correctly measure a patient's blood pressure. For example, a patient with and arm circumference of 30 centimeters would require an adult type cuff, while a patient with an arm circumference of 20 centimeters might use a child cuff. It is important that the cuff be chosen to match the patient's arm type.
As previously described, conventional NIBP systems initiate a blood pressure measurement by inflating the pressure cuff above the patient's systolic pressure level. It is therefore necessary to estimate a supra-systolic pressure level for a given patient. Additionally, the initial supra-systolic pressure level estimate should ideally be only slightly greater than the patient's actual systolic pressure level. If, for example, a supra-systolic estimate surpasses the patient's actual systolic pressure level by an excessive amount, the duration of the NIBP determination may be unnecessarily prolonged and the pressure cuff may cause pain or discomfort during initial inflation.
Another problem with conventional NIBP systems is that it is difficult to precisely estimate a supra-systolic pressure level that only slightly exceeds a patient's actual systolic pressure level for each of a variety of different patients. Since a child typically has a lower blood pressure than an adult, knowledge of the cuff type could allow better choice of the initial target pressure.